Preprints
https://doi.org/10.5194/egusphere-2023-2600
https://doi.org/10.5194/egusphere-2023-2600
05 Dec 2023
 | 05 Dec 2023

Contribution of fluorescent primary biological aerosol particles to low-level Arctic cloud residuals

Gabriel Pereira Freitas, Ben Kopec, Kouji Adachi, Radovan Krejci, Dominic Heslin-Rees, Karl Espen Yttri, Alun Hubbard, Jeffrey M. Welker, and Paul Zieger

Abstract. Mixed-phase clouds (MPC) are key players in the Arctic climate system due to their role in modulating solar and terrestrial radiation. Such radiative interactions critically rely on the ice content of MPC which, in turn, also depend on the availability of ice nucleating particles (INP). INP sources and concentrations are poorly understood in the Arctic. Recently, INP active at high temperatures were associated with the presence of primary biological aerosol particles (PBAP). Here, we investigated for a full year the abundance and variability of fluorescent PBAP (fPBAP) within cloud residuals, directly sampled by a multiparameter bioaerosol spectrometer coupled to a ground-based counterflow virtual impactor inlet at the Zeppelin Observatory (475 m asl), Ny-Ålesund, Svalbard. fPBAP concentrations (10-3–10-2 L-1) and contributions to coarse-mode aerosol (0.1 to 1 in every 103 particles) within cloud residuals were found to be close to those expected for concentrations of high-temperature INP. Transmission electron microscopy also confirmed the presence of fPBAP, most likely bacteria, within the cloud residual samples. Seasonally, our results reveal an elevated presence of fPBAP within cloud residuals in summer. Parallel water vapor isotope measurements point towards a link between summer clouds and regionally sourced air masses. Low-level MPC were predominantly observed at the beginning and end of summer, and one explanation for their presence is the existence of high-temperature INP. In this study, we present observational evidence that fPBAP may play an important role in determining the phase of low-level Arctic clouds. These findings have potential implications for the future description of sources of cloud condensation nuclei given ongoing changes in the hydrological and biogeochemical cycles that will influence the PBAP flux in and towards the Arctic.

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Journal article(s) based on this preprint

13 May 2024
Contribution of fluorescent primary biological aerosol particles to low-level Arctic cloud residuals
Gabriel Pereira Freitas, Ben Kopec, Kouji Adachi, Radovan Krejci, Dominic Heslin-Rees, Karl Espen Yttri, Alun Hubbard, Jeffrey M. Welker, and Paul Zieger
Atmos. Chem. Phys., 24, 5479–5494, https://doi.org/10.5194/acp-24-5479-2024,https://doi.org/10.5194/acp-24-5479-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Bioaerosols can participate in ice formation within clouds. In the Arctic, where global warming...
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